A study will be made of mitochondrial functions during diapause and during the termination of diapause. Emphasis will be on metabolic processes in fatbody mitochondria in insect larvae maintained under different photoperiodic regimens. The role of photoperiod in termination of larval diapause will be investigated, with emphasis on definition of the concept of "diapause intensity". This study will also involve application of the Photoperiodic Determination Theory to diapause termination phenomena. The Photoperiodic Determination Theory will be further investigated using both biological experimentation and computer simulation. Attempts will be made to apply the theory to behavioral and development periodism in both animals and plants. The theory will be tested against observed temperature effects, light intensity effects, and natural selection pressures.